I have recently noticed an automatic transmission malfunction on my '95 E320 wagon (W124) with 130,000miles.
The transmission operates silky smooth in all ranges, EXCEPT, when coasting up to a stopsign at about 10mph, I get a Rough Downshift (clunk).
[I have had this problem on my 123 diesels, and it always turns out to be a vacuum problem [leak], which is reducing vacuum to the modulator.]
I checked the M104 engine for loose vacuum lines/hoses and have found none. I pulled the vacuum connector from the second intake plenum and checked the line with a mighty vac & it held good vacuum (I think that on leads to the vac modulator on the automatic trans).
[I also have a check engine light on, but believe this is unrelated to the timing of the trans problem. (this car has the original engine harness).]
Any suggestions or components to check/replace are welcome.